When regenerating cellulose material in an acidic spin bath containing zinc sulphate,disturbancies frequently occur due to the presence of clogging material. The origins of the clogging material are different. One and the most important source are solid by-products, i.e. elementary sulphur and zinc sulphide, which are formed when the dissolved xanthogenated celluloses are regenerated to cellulose and carbon disulphide. Other examples of clogging by-products are hemicelluloses and resins derived from the cellulosic raw material itself and transfered to the spin bath where they cause deposits.
One method of reducing these disadvantages is to add cationic surface active compounds to the spinning baths. Thus, in Japanese Patent No. 48006409 it is suggested to add N,N'-polyoxyethylene-N-long chain-alkyl alkylene-diamines and N,N',N'-polyoxyethylene-N-long chain-alkyl alkylene-triamines into the spin bath as dispersants for sulphur particles which cause blockages in spinning nozzles. The long-chain alkyl group contains from 10 to 20 carbon atoms. The number of oxyethylene groups are from 1 to 8 for each substitution position and their sum is from 2 to 10. However, these additives have a rather limited ability to disperse sulphur, especially when the amounts thereof is high.
In Japanese Patent Application No. 54101916 it is suggested to add polyoxyethylene alkyl mono- and diamide polyalkylene polyamines to further reduce the clogging of nozzles. Examples of the used polyalkylene polyamines are triethylene tetramine and tetraethylene pentamine. The number of carbon numbers in the fatty acids used for preparing the said compounds is preferably from 12 to 22, while the number of groups derived from ethylene oxide in the molecule is from 6 to 12. Although these polyamines have a good dispersing effect they have a serious drawback since they are not stable in hot acid solutions and are hydrolyzed at high temperature in the spin bath. Consequently, after some time their effect is essentially reduced.
The degradation of the additive can be compensated by addition of higher dosages of the additives. However in practice the resulting products of the hydrolysis, i.e. the fatty acids produced especially during reconditioning of the spin bath, enhances the clogging. Together with elementary sulphur and/or zinc sulphide and resins they form black particles, which are very difficult to disperse.
It is therefore an object of the invention to overcome the deficiencies of the prior art.